ESPE Abstracts

Background: Mosaic Turner syndrome (TSM) commonly occurs in the form of 45,X/46,XX and 45,X/46,Xiq, although mosaicism including the presence of a Y chromosome has been well documented. It is associated with increased risk of gonadoblastoma (GB).

Objective and hypotheses: To date, there are only six reported cases of TSM with a trisomy 18 karyotype, and only two of these were phenotypically female with 45,X, 47,XY+18 karyotype.

Method: We present the case of an infant born with dysmorphic features noted at birth (webbed neck, low set ears and broad chest). G banded karyotype and interphase FISH of blood showed 45,X in 95% and 47,XY +18 (Edwards syndrome) in 5% of cells analysed. However, interphase FISH of buccal cells showed only 45,X. Increased nuchal fluid, suggestive of Edward’s syndrome had been detected at 13 weeks gestation on ultrasound but had resolved on follow-up scan at 15 weeks hence amniocentesis was not preformed. Renal ultrasound and echocardiogram were normal. Owing to presence of SRY, an elective gonadectomy was performed at 13 months of age. There were bilateral streak ovaries with early evidence of GB bilaterally, rudimentary uterus and bilateral fallopian tubes with unilateral ectopic adrenal tissue identified. Interphase FISH of the gonadal tissue was similar to the blood findings with 45,X in 86% of cells and 47,XY+18 in 14% of cells analysed.

Results: She is now 2 years old, growing and developing well.

Conclusion: This case highlights a rare karyotype of TSM and Edwards syndrome in the same patient. Current investigations are ongoing as to the possible causes for this unusual finding. This case was also associated with a finding of bilateral gonadoblastoma. To the authors’ knowledge this is the only case with the above karyotype with gonadoblastoma reported.